Technical Field
The present invention relates to a magnetic element using skyrmions as a memory, a skyrmion memory, a skyrmion memory circuit, a skyrmion memory device, a skyrmion-memory-device embedded solid-state electronic device, a data recording apparatus, a data processing apparatus, and a communication apparatus.
Related Art
A magnetic element is known that uses the magnetic moment of a magnet as digital information. A skyrmion memory using skyrmions, which is a magnetic element, includes the element structure of a nonvolatile memory that does not require power when holding nanoscale information. Based on advantages such as ultra-high density resulting from the nanoscale magnetic structure, this magnetic element is expected to be used as a high-capacity information storage medium, and the importance thereof increases when used as a memory device of an electronic device.
Magnetic shift registers have been proposed, mainly by IBM in the US, as candidates for next-generation magnetic memory devices. A magnetic shift register drives a magnetic domain wall to transfer the magnetic moment arrangement thereof through a current, and reads stored information (see Patent Document 1).
FIG. 36 is a schematic view of the principles of driving a magnetic domain wall with current. The domain wall is a boundary of a magnetic region where the orientations of magnetic moments are phase-inverted. In FIG. 36, the domain walls in a magnetic shift register 1 are shown by solid lines. The magnetic domain walls are driven by causing current with the orientation indicated by the arrows to flow in the magnetic shift register 1. By driving the domain walls, the magnetism caused by the orientation of the magnetic moment positioned above the magnetic sensor 2 changes. This magnetic change is sensed by the magnetic sensor 2, and magnetic information is derived.
However, this type of magnetic shift register 1 requires a large current when moving the magnetic domain walls, and there is a disadvantage that the transfer velocity of the magnetic domain walls is low. Furthermore, in the case of a nano-size domain, a problem occurs that spin reversal occurs due to thermal disturbance. The reliability guarantee for an LSI demands data holding for 10 years.
Therefore, the inventors of the present application proposed a skyrmion magnetic element that uses skyrmions generated in the magnet as a storage unit (see Patent Document 2). In this proposal, the inventors of the present application showed that it is possible to drive skyrmions with current. Furthermore, the details concerning the motion of the skyrmions being able to be driven by current were made clear, and the results were shown (see Non-Patent Document 2).
In this Specification, an arrangement in which the drive current and the transfer direction of the skyrmions are substantially parallel is defined as a longitudinal transfer arrangement. When using such a longitudinal transfer arrangement as a memory, electrodes that apply current are provided to both ends of the fine line structure of the magnet having the skyrmions. In order to handle the skyrmions as information units, a sensor that senses the skyrmions is provided at a prescribed location along the fine lines of the magnet. Therefore, time is needed to transfer the skyrmions to the prescribed position of the sensor. This is the same as in the magnetic shift register proposed by IBM in the US (see FIG. 36).
However, it became clear that there was a major problem that the transfer velocity of the skyrmions is low in the longitudinal transfer arrangement (see Non-Patent Document 2). As a second issue to be addressed, there is a problem that the skyrmion drive current density is large in the longitudinal transfer arrangement. In a case where the transfer velocity of the skyrmions in the longitudinal transfer arrangement is 15 m/s, the current density becomes a large value of 2×1011 Am−2 (see Non-Patent Document 2). When handling the skyrmions as information units, it was made clear that there is a problem of the transfer velocity of the skyrmions is slow, and therefore that the current density for driving is large.